1. Field of the Invention
The present invention relates to an occupant crush protection system which protects an occupant of a vehicle from impact shocks when the vehicle comes into collision with an object such as a car or a wall.
2. Description of the Related Art
A seatbelt retraction device is a well-known device of protecting an occupant of a vehicle from an accidental collision. Such a seatbelt retraction device includes an electric motor, a motor driving circuit and a relay circuit to retract a seatbelt so that an occupant can fasten the seatbelt without slackness. Such a seatbelt retraction device may include a pre-collision sensor which predicts a collision. In this case, the electric motor retracts the seatbelt according to a signal of the pre-collision sensor. Usually, the electric motor is powered by a vehicle battery trough the relay circuit, which is always turned on so that the slackness of the seatbelt can be always controlled. Accordingly, a considerable amount of electric power is wasted in the motor driving circuit even when the seat belt system is not operated.